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    <title>ShellCheck: SC3002 – In POSIX sh, extglob is undefined.</title>
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    <h1>SC3002 – ShellCheck Wiki</h1>
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    <h2 id="in-posix-sh-extglob-is-undefined">In POSIX sh, extglob is
undefined.</h2>
<p>(or "In dash, ... is not supported." when using
<code>dash</code>)</p>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC3002.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="co">#!/bin/sh</span></span>
<span id="cb1-2"><a href="SC3002.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="fu">rm</span> <span class="pp">!(*</span>.hs<span class="pp">)</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<p>Either switch the shebang to a shell that does support extglob, like
<code>bash</code> or <code>ksh</code>, or rewrite in terms of a loop
with a <code>case</code> or <code>grep</code> match:</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC3002.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="co">#!/bin/sh</span></span>
<span id="cb2-2"><a href="SC3002.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="cf">for</span> file <span class="kw">in</span> <span class="pp">*</span></span>
<span id="cb2-3"><a href="SC3002.html#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="cf">do</span></span>
<span id="cb2-4"><a href="SC3002.html#cb2-4" aria-hidden="true" tabindex="-1"></a>  <span class="cf">case</span> <span class="st">&quot;</span><span class="va">$file</span><span class="st">&quot;</span> <span class="kw">in</span></span>
<span id="cb2-5"><a href="SC3002.html#cb2-5" aria-hidden="true" tabindex="-1"></a>    <span class="pp">*</span><span class="ss">.hs</span><span class="kw">)</span> <span class="fu">true</span><span class="cf">;;</span></span>
<span id="cb2-6"><a href="SC3002.html#cb2-6" aria-hidden="true" tabindex="-1"></a>    <span class="pp">*</span><span class="kw">)</span> <span class="fu">rm</span> <span class="st">&quot;</span><span class="va">$file</span><span class="st">&quot;</span> <span class="cf">;;</span></span>
<span id="cb2-7"><a href="SC3002.html#cb2-7" aria-hidden="true" tabindex="-1"></a>  <span class="cf">esac</span></span>
<span id="cb2-8"><a href="SC3002.html#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="cf">done</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>Extglobs are extensions in bash and ksh, while your shebang says
you're using <code>sh</code> or <code>dash</code>.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>If you only intend to target shells that supports this feature, you
can change the shebang to a shell that guarantees support, or <a
href="ignore.html">ignore</a> this warning.</p>
<p>You can use <code># shellcheck disable=SC3000-SC4000</code> to ignore
all such compatibility warnings.</p>
<h3 id="related-resources">Related resources:</h3>
<ul>
<li>Help by adding links to BashFAQ, StackOverflow, man pages, POSIX,
etc!</li>
</ul>
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